Activists slam 'obnoxious and wrong’ parade float honoring MLK Jr.’s assassin James Earl Ray
Racist truck in Pennsylvania (Screengrab / Twitter)

To celebrate Dr. Martin Luther King Jr. day, a Pennsylvania man decorated his pickup with a black mannequin hanging from a rope, a Confederate flag flying on a pole and a sign reading, “In loving memory of [King’s murderer] James Earl Ray,” WJAC reports.

Johnston Police are probing the display, which was shared across Facebook on Monday and Tuesday.

"We're actively working on this with the Johnstown Police Department ... to determine whether there is anything more to this than the photo," First Assistant District Attorney Heath Long told ABC News. Investigators told the news organization they’re looking into whether the driver engaged in potentially criminal behavior outside the perimeters of free speech.

Interim police Chief Jeff Janciga said the display is "in poor taste any time of the year,” but affirmed the Johnston Police Department’s commitment to the First Amendment.

"Look at the Westboro Baptist Church and what they do at funerals," Janciga said. “Even though its an emotional time for people (mourning the loss of a loved one), their hateful speech is protected.”

While local NAACP head Alan Cashaw called the truck's imagery “hate,” the Americans Civil Liberties Union sent Pennsylvania’s 6 News a statement reading in part:

“He has a right to say those things. The First Amendment gives you the right to say things that are obnoxious and wrong, and this is both.”